Tensionable elastic screen bottom

ABSTRACT

A screen bottom has a plate with sieve opening consisting of an elastic plastic material and having zones engaged by supporting or fixing strips and devoid of sieve openings. At the ends of the plate are clamping members. The device is particularly characterized by a supporting grid-like structure made of flexible, elastic, somewhat stretchable or non-elastic materials which is so arranged that when the plate is not tensioned the supporting structure extends wave-like downwardly with respect to the plate, the extension of the sieve surface being determined by the difference in length between the wave-like curves of the hanging grid-like structure and the length of the plate.

United States Patent Wehner TENSIONABLE ELASTIC SCREEN BOTTOM inventor: Albert Wehner, Wieladingen, Germany Assignee: Lehmann Hein 8: Co. AG, Dusseldorf, Germany Filed: Dec. 11, 1969 Appl. No.: 884,066

US. Cl. ..209/403, 209/399, 209/405,

Int. Cl. .....B07b 1/04 Field of Search.. ....209/403, 405, 408, 310, 402, 209/233, 392, 395, 396, 399; 245/2; 15/368;

v References Cited FOREIGN PATENTS OR APPLICATIONS 4/1935 Germany ..209/31O [15] 3,684,091 [4s] Aug. 15, 1972 Primary Examiner-Frank Wt Lutter Assistant Examiner-william Cuchlinski, Jr.

Attorney-Richards & Geier [57] ABSTRACT A screen bottom has a plate with sieve opening consisting of an elastic plastic material and having zones engaged by supporting or fixing strips and devoid of sieve openings. At the ends of the plate are clamping members. The device is particularly characterized by a l6 Clains, 19 Drawing figures minnows 15 I912 a 684,091 A SHEET 1 OF 3 I Ii ::-*-I'1-H- I I I I I I I I I I p L L INVENTOR ALBERT WERNER ATTORNEY I3 PATENTEDAuc 15 me SHEET 2 BF 3 Fig. 5

INVENTOR ALBERT WERNER ATTO RNEY S PATENTEIJAUEIS 1912 3.684.091

SHEET 3 BF 3 I IIIHHTIHHIII IIIII'IIIlIIII *[Hllnllllllllr INVENTOR ALBERT WERNER TENSIONABLE ELASTIC SCREEN BO'I'IOM This invention relates to a screen bottom with a plate, hereinafter termed a sieve plate or sieve bottom consisting preferably of an elastic plastic material which is tensioned by zones upon supports located at corresponding distances. The tensioning taking place either by the supports themselves or by means of carriers located in a machine.

Known sieve bottoms of this type which are provided, for example, with an extensible sieve plate of plastic material, are held with suitable spacing by fixing strips which do not have any sieve openings and which are used for attachment to fixing supports located in a sieve frame.

In other known sieve bottoms the elastic sieve plate is continuously flatly tensioned upon fixing supports which have been previously firmly connected with the sieve frame, and is held in stretched condition by fixing strips devoid of holes and extending in the plane of the sieve plate.

According to another later developed sieve bottom, non-elastic cross-sectional members are embedded in the elastic material of the sieve bottom. This has the undesirable effects of removing elasticity and the elimination of effective forces of the sieving machine which are required for the sieving process. This sieve bottom is very expensive to manufacture and has the further drawback that elastic cross-sectional members particularly desirable from the point of view of wear resistance are made small or are ineffective. Furthermore, it was found that in this construction the tensile stress of the elastic material gives in after the elastic cross-sections have been somewhat worn out by the material being sieved, that the sieve bottoms tensioned by zones are stretched and that the effectiveness of the individual zones drops.

An object of the present invention is to eliminate the drawbacks of existing constructions.

Another object is the provision of new and most effective constructions of elastic screen or sieve bottoms tensioned by zones.

Yet another object is the provision of non-elastic or somewhat elastic screen or sieve bottoms which are supported by zones. 1

Other objects of the present invention will become apparent in the course of the following specification.

In the accomplishment of the objectives of the present invention it was found desirable to introduce a novel suspension device preferably located under the actual screen or sieve bottom and having cross-sectional members which consist of a substance which is less elastic than the screen bottom, or is a rigid but elastically bendable material, such as steel bands or wires, or has chain-like, or link-like structures, etc. This suspension device can be provided with additional I-Ieretofore, when a device of this type was being fixed there was often the drawback that the elastic screen will be shifted in the sieving direction, so that dislocations or openings are produced which detrimentally afl'ect the sieving process. To avoid this it is possible to connect the tensioning cross-sectional members which by themselves already prevent this shifting with additional claw-like members which lie behind specially provided path sections of the machine after the sieve bottom has been placed into the machine. The transverse rigid members can also be provided in the supporting device in such manner that prior to the fixing of the screen bottom they form. jointly with the supporting device an arc extending toward the actual screen bottom and the tensioning strips. Preferably bolts, which can be provided with connecting means, hollow and full rivets, as well as scnews, fixtures and the like, are used for all connections of the sieve bottom with the supporting device, of the supporting device with the transverse members, and of the tensioning support of the sieve bottom with the above-lying members, unless, as above stated, vulcanization, gluing and similar procedures are used.

The sieve bottom of the present invention can be also efi'ectively utilized in constructions wherein the stretching of fine weaves of bronze, spring steel or non rusting steels had always been a problem, since the tensioning forces could not be controlled and thus the weave would tear shortly behind the tensioning hooks.

The invention will appear more clearly from the following detailed description when taken in connection with the accompanying drawings showing by way of example only, preferred embodiments of the inventive idea.

In the drawings:

FIG. 1 is a side view of a sieve bottom constructed in accordance with the principles of the present invention.

FIG. 2 is a top view of the sieve bottom shown in FIG. 1.

FIG. 3 is similar to FIG. 1 but shows the sieve bottom in a stretched condition.

FIG. 4 is a side view of a different sieve bottom in a stretched condition.

FIG. 4a shows the same sieve bottom in an unstretched condition.

FIG. 5, 6, 7 and 8 are diagrammatic side views of different sieve bottoms of the present invention.

FIGS. 9, l0 and 11 are diagrammatic side views, partly in section, of parts of different sieve bottoms of the present invention.

FIG. 12 is a section through a transversely tensioned sieve bottom of the present invention.

FIG. 13 is a partial side view of the sieve bottom shown in FIG. 12.

FIG. 12 is a top view partly in section of yet another sieve bottom of the present invention.

FIG. 14a is a side view of the sieve bottom shown in FIG. 14.

FIG. 15 is a diagrammatic side view with parts broken off illustrating the application of the present invention to a non-elastic sieve bottom.

FIG. 16 is a diagram illustrating another application of the principle shown in FIG. 15.

FIG. 17 is a side view of yet another sieve bottom of the present invention.

The screen bottom has a sieve plate member as shown in FIG. 1 in its unstretched condition in which its tensioning strips 2 are curved downwardly. Opposed edges of the plate 1 are held by tensioning hooks 3. The untensioned zone of this construction is indicated by the length a in the drawing.

The sieve plate 1 carries transversely extending supporting or attaching strips 1' which are devoid of sieve openings (FIG. 2). All or some of the ends of longitudinally extending strips 2 are folded into the hooks 3. In addition they can also be firmly connected with the hooks by riveting or the like. The strips 2 and the hooks 3 constitute a supporting tackle member. Holes 4 are provided in the sieve between the strips 1 and 2 which do not have any holes. Connecting bolts 5 are used to support the sieve bottom upon a frame.

'FIG. 3 shows the same sieve plate but in a stretched condition. The distance a indicates the stretched zone. The sieve plate is supported upon rods 6 of a frame or a sieve machine in such manner that non-perforated portions of the sieve bottom are engaged by the supporting rods. In this stretched condition the sieve bottom and its tensioning means extend completely parallel to each other. Thus the supporting means provide a permanent hold for the sieve bottom, as well as the desired support of the elastic sieve bottom, so that the sieving energy of the sieve machine is made much more effective. The extent of the tensioning of the sieve bottom is indicated by the two lengths a showing the extent of the tensioning movement of the hooks 3.

FIGS. 4 and 4a show a construction wherein the longitudinal strips 2 carry transverse supporting members 7. The members 7 are attached only to the strips 2. When the device is stretched the members 7 will firmly engage the sieve bottom 1 from the bottom and will provide a firm constant hold. The members 7' are preferably made of somewhat stretchable plastic materials, pressed wood, light metal or the like, so as to keep the weight of the extra sieve bottom as light as possible and to avoid breakages resulting from swing- FIG. 8 shows a sieve bottom 1 the actual sieving surface of which is located under the supporting strips 2 so that after tensioning the supporting strips 2 lie as a reinforcement on top or" the sieving surface.

FIG. 9 shows in section a portion of a sieve bottom 1A of the present invention which is provided with openings 5" and/or 5" enclosed by holders and used to receive pins 8 carried by the supporting strips 2. The pins 8 may be made of metal or a plastic material.

FIG. It) shows a construction wherein the supporting strips 2 are made of separate pieces connected by joints 2'. After tensioning the strip pieces as well as their joints will extend parallel to each other and will lie against the sieving surface of the sieve bottom 1.

FIG. 11 illustrates a sieve bottom having a downwardly extending sleeve 1" which is directly connected therewith by vulcanization or gluing. The strip 2 passes through the sleeve 1' FIGS. 12 and 13 show a sieve bottom wherein the supporting strips 2 carry angular clamps 9 which engage supports of a sieve machine and which connect ing, particularly when plastic and pressed wood are;

used.

FIG. 5 shows a construction of the present invention wherein the transverse members 7 are located between the sieve bottom 1 and the supporting strips 2 and are firmly connected with them.

FIG. 6 shows a construction wherein the sieve bottom 1 and the supporting strips 2 are located above the transverse members 7.

FIG. 7 shows a sieve bottom of the present invention which is particularly suitable for fine sieving. In this construction second sieving bottom 1" having finer sieve openings is located above the sieve bottom 1 which can have less fine openings. The second sieving bottom may have the same elastic structure and be provided with fixing members 5. These connecting fixing members may consist of the usual bolts or rivets, or they may consist of specially shaped press button-like pins made of plastic material. All three ends, namely, those of the sieve bottom 1, the sieving bottom 1" and of the strips 2 are embedded or fixed in the hooks 3. If necessary another transversely extending supporting member 7' can be located under the sieve bottom 1 with larger openings or between the sieving bottom 1" with finer openings and the sieve bottom 1.

the strips with the sieve bottom. This construction prevents the shifting of the device in the sieve direction indicated by an arrow in FIG. 12.

FIGS. 14 and 14a show a sieve bottom wherein the transverse cross-sectional supporting pieces 7" are arranged in such large quantities upon the supporting strips 2 that they actually operate as a net. The left hand portion of FIG. 14 shows the bottom 1 as having been removed, so that the arrangement of the underlying pieces upon the strips is clearly visible.

FIG. 15 shows the application of the principles of the present invention to non-elastic very sensitive sieve bottoms consisting, for example, of fine weaves for filtering purposes. In this case the sieve bottom 6 is arranged in curves (contrary to the elastic bottoms of rubber or plastics), while the supporting strips 2b are then made of elastic material; they extend in a flat plane and are curved. Of importance is that the bottom should always remain upon the elastic supporting strips, for example, by connecting members 7.

In this construction the non-elastic sieve bottom and the elastic supporting strips do extend substantially parallel to each other. The construction of the elastic strips and their connections 7 with the sieve bottom are such that they both extend substantially parallel to each other and that when the elastic strips are pulled no excessive load is exerted upon the sieve bottom. To attain this all connections 7 should be carried by the elastic strips and only the elastic strips (without the sieve bottom) are attached to the hooks 3.

FIG. 16 shows the application of the same principle to the so-called tensioned wave-line sieve bottom described in greater detail in German Pat. No. 1,266,372. In accordance with the present invention a fine elastic or half-elastic sieve bottom 1" is arranged on top of the sieve mat 1c which is extensible but is of less fine structure.

The sieve bottom 1" and the sieve mat 10 extend parallel to each other in the shape of a wave between carriers I and II. This location changes depending upon the measure of the sieve frequency.

In the above described constructions the elastic strips were fixed solely by their ends to the frame. However, FIG. 17 illustrates a construction wherein the elastic strips consist of rubber strips extending through slotted tubular carriers and used as a tensionable bottom carrier. In accordance with the present invention there are two cross-sectional supporting members 2c and 2' mounted respectively above and below the transverse connection 7, whereby preferably the member 2' is placed in the plane of the usual sieve bottom 1. The tensioning hooks 3 can be adapted to the slotted tubular cross-section of the transverse members 7, so that they will form jointly as a support for the sieve bottom.

I claim:

' 1. A screen bottom, comprising a sieve plate member having sieve openings and zones devoid of sieve openings, a supporting tackle member having parallel elongated strips and hooks at the ends of said strips, said hooks being connected to opposite ends of said plate member, said two members having different elastic qualities and in their untensioned state the less elastic of the two members lies in arched arrangement relatively to the more elastic of the two members and is larger in length than the more elastic member, and upon tensioning of the screen bottom the one of said members which was initially the smaller in length and more elastic is extended to the length of the other one of said members which was initially the larger in length and less elastic member.

2. A device in accordance with claim 1, wherein said strips form a single hanging down curve extending between the hooks.

3. A device in accordance with claim 1, comprising a second finer elastic sieving bottom located above the first-mentioned sieving bottom, the two sieving bottoms and said strips extending when tensioned parallel to each other.

4. A device in accordance with claim 1, wherein said strips extend wave-like above said sieve bottom.

5. A device in accordance with claim 1, comprising holders fixed to said sieve bottom by vulcanization or glueing and carrying said strips.

6. A device in accordance with claim 1, wherein said sieve bottom consists of flexible fine weave of bronze or spring steel, said strips being elastic.

7. A device in accordance with claim 1, wherein said strips consist of a material which is elastic but less elastic than the material of which said sieve bottom is made.

8. A device in accordance with claim 7, wherein said 9. A device in accordance with claim 8 wherein said strips consist of a flexible material consisting of Perlon, steel strips or weaves.

- 10. A screen bottom, comprising a sieve plate member having sieve openings and zones devoid of sieve openings, a supporting tackle member having spring steel binder or plastic.

parallel elongated strips, said strips forming a plurality of hanging down curves extending between alternate zones, a plurality of transverse supporting members located below said strips, said transverse supporting members being located from the group of materials consisting of plastics, wood, pressed wood and light metal means connecting said transverse supporting members to said strips and to said sieve plate along said 8% c fi niildib gi irlifi i siiiilfivtiil member, said sieve plate member and said supporting tackle member having different elastic qualities and in their untensioned state the less elastic of the two members lies in arched arrangement relatively to the more elastic of the two members and is larger in length than the more elastic member, and upon tensioning of the screen bottom the one of said members which was initially the smaller in length and more elastic is extended to the length of the other one of said members which was initially the larger in length and less elastic member.

11. A device in accordance with claim 10, wherein said transverse supporting members are fixed solely to said strips, said transverse supporting members engaging the lower surface of said sieve bottom in the zones devoid of openings when said strips are tensioned.

12. A device in accordancewith claim 10, wherein said transverse supporting members are fixed to said strips and to the lower surface of said sieve, said transverse supporting members extending along said zones.

13. A device in accordance with claim 1, comprising holders carried by said sieve bottom, and pins carried by said strips and adapted to engage said holders to connect said sieve bottom with said strips.

14. A device in accordance with claim 10, wherein said strips consist of pivoted non-elastic sections.

15. A device in accordance with claim 10, comprising angular clamps connecting said strips with said sieve bottom.

16. A device in accordance with claim 10, wherein said strips are connected to said transverse supporting members on top and bottom, the top connections extending substantially in the plane of said sieve bottom when the sieve bottom is tensioned. 

1. A screen bottom, comprising a sieve plate member having sieve openings and zones devoid of sieve openings, a supporting tackle member having parallel elongated strips and hooks at the ends of said strips, said hooks being connected to opposite ends of said plate member, said two members having different elastic qualities and in their untensioned state the less elastic of the two members lies in arched arrangement relatively to the more elastic of the two members and is larger in length than the more elastic member, and upon tensioning of the screen bottom the one of said members which was initially the smaller in length and more elastic is extended to the length of the other one of said members which was initially the larger in length and less elastic member.
 2. A device in accordance with claim 1, wherein said strips form a single hanging down curve extending between the hooks.
 3. A device in accordance with claim 1, comprising a second finer elastic sieving botTom located above the first-mentioned sieving bottom, the two sieving bottoms and said strips extending when tensioned parallel to each other.
 4. A device in accordance with claim 1, wherein said strips extend wave-like above said sieve bottom.
 5. A device in accordance with claim 1, comprising holders fixed to said sieve bottom by vulcanization or glueing and carrying said strips.
 6. A device in accordance with claim 1, wherein said sieve bottom consists of flexible fine weave of bronze or spring steel, said strips being elastic.
 7. A device in accordance with claim 1, wherein said strips consist of a material which is elastic but less elastic than the material of which said sieve bottom is made.
 8. A device in accordance with claim 7, wherein said strips consist of stretchable material consisting of spring steel binder or plastic.
 9. A device in accordance with claim 8 wherein said strips consist of a flexible material consisting of Perlon, steel strips or weaves.
 10. A screen bottom, comprising a sieve plate member having sieve openings and zones devoid of sieve openings, a supporting tackle member having parallel elongated strips, said strips forming a plurality of hanging down curves extending between alternate zones, a plurality of transverse supporting members located below said strips, said transverse supporting members being located from the group of materials consisting of plastics, wood, pressed wood and light metal means connecting said transverse supporting members to said strips and to said sieve plate along said zones, said supporting tackle member further having hooks connected to opposite ends of said sieve plate member, said sieve plate member and said supporting tackle member having different elastic qualities and in their untensioned state the less elastic of the two members lies in arched arrangement relatively to the more elastic of the two members and is larger in length than the more elastic member, and upon tensioning of the screen bottom the one of said members which was initially the smaller in length and more elastic is extended to the length of the other one of said members which was initially the larger in length and less elastic member.
 11. A device in accordance with claim 10, wherein said transverse supporting members are fixed solely to said strips, said transverse supporting members engaging the lower surface of said sieve bottom in the zones devoid of openings when said strips are tensioned.
 12. A device in accordance with claim 10, wherein said transverse supporting members are fixed to said strips and to the lower surface of said sieve, said transverse supporting members extending along said zones.
 13. A device in accordance with claim 1, comprising holders carried by said sieve bottom, and pins carried by said strips and adapted to engage said holders to connect said sieve bottom with said strips.
 14. A device in accordance with claim 10, wherein said strips consist of pivoted non-elastic sections.
 15. A device in accordance with claim 10, comprising angular clamps connecting said strips with said sieve bottom.
 16. A device in accordance with claim 10, wherein said strips are connected to said transverse supporting members on top and bottom, the top connections extending substantially in the plane of said sieve bottom when the sieve bottom is tensioned. 